INVERTEBRATES

The specimens in this room of the American Museum of Natural History are chiefly Invertebrates. In the foreground is the bronze bust of Darwin presented by the New York Academy of Sciences to the Museum on the occasion of the Darwin Centenary in 1909, at which time this pavilion was designated as the Darwin Hall. The installation in the Alcoves is designed to give a synopsis of the animal kingdom and the relationships between the various groups, while the special exhibits, in other portions of the hall, are intended to illustrate certain biological principles. The visitor, passing around the hall from left to right, finds that the progression is from the lowest forms of animal life to the highest and most complex, i.e., from the Protozoa to the Primates, including Man. Many of the in-vertebrates, particularly the lowest forms, are so minute that they can be seen only by the aid of a compound micro-scope. In these instances the specimens are represented by models in glass and wax, many times enlarged.

ALCOVE 1--Protozoa. This group contains the lowest forms of animal life AMONG THE Invertebrates. They are all single-celled individuals, some being found in swamps and stagnant water and others in the ocean.

ALCOVE 2—Sponges. Many of the "glass" sponges are exceedingly beautiful; certain other specimens are coated with wax, tinted to show the natural color of the flesh of the animal.
ALCOVE 3—Polyps. Here are shown the coral animals and their relatives; plant-like hydroids, frequently mistaken for seaweeds; jelly-fishes, brilliantly colored sea anemones, sea fans and sea plumes, reef corals and the precious coral of commerce. In front of the window is a life-size model in glass of the beautiful Portuguese man-of-war.
ALCOVE 4—Flatworms, the best known species of which include the tapeworms. There are also exhibited parasitic and free-living flatworms, the latter, which inhabit both salt and fresh water, being shown by enlarged models in the right-hand alcove case. These in particular well illustrate the great diversity of color and detail found in this group.

ALCOVE 5—Roundworms. Here may be found an enlarged model of the common roundworm, or stomach worm of the horse (Ascaris) , showing the internal structure.
ALCOVE 6—Rotifers. These are minute wheel animalcules, comprising many exquisite and grotesque forms. They are aquatic and found mainly in fresh water.
ALCOVE 7—Sea mats, minute plant-like or encrusting animals which lead the colonial form of life, and the lamp shells, which superficially resemble clams but by structure are more closely related to the worms and starfishes.
ALCOVE 8—Sea stars, the pest of the oyster beds; brittle stars, so called because of their tendency to drop one or more arms when handled; sea cucumbers and sea lilies, also sea urchins, which form an important article of food in Europe and the West Indies.
ALCOVE 9—Annulates, worms whose bodies are made up of rings or segments. They inhabit both salt and fresh water. A number of them are illustrated by a series of enlarged models. The houses that these annulated Invertebrates build are frequently beautiful and interesting.
In the window is a group showing a section of a mud-flat on the New England coast, which graphically depicts the variety, habits and life of marine worms.

ALCOVE 10—Arthropods, which include the familiar crabs, lobsters, insects and their relatives. The case in the center of the alcove contains a model showing the anatomy of the common lobster, also enlarged models showing the heads of various insects. On the wall are the two largest specimens of lobster (weighing thirty-one and thirty-four pounds respectively) that have ever been taken. The largest of the arthropods is the giant spider-crab of Japan, which has a spread of about ten feet.
ALCOVE 11—Mollusks. The exhibit includes marine, fresh-water and land animals. Special attention should be given to the enlarged models of the common clam and oyster, displayed in the center case. Other collections of mollusks will be found on the third floor.
ALCOVE 12—Chordates, including vertebrates. The vertebrates include the largest and most intelligent animals, culminating in Man, who still bears witness to his chordate ancestry in the reappearance of a chorda (cartilaginous spine) and gill clefts during embryonic life. In this section are specimens of the lancelet Amphioxus, related to the primitive group from which the vertebrates developed.

The visitor of the American Museum of Natural History Invertebrates should now go to the Tower Alcove which contains a comprehensive synoptic series of stony corals. Return to the center of the hall and examine the four large models of the malaria mosquito, enlarged seventy-five diameters or in volume 400,000 times the natural size.

In the windows around the hall are the Sea Worm,' Shore Mollusk and Wharf Pile Groups, the last-named being a reproduction of the piles of an old wharf at Vine-yard Haven, Massachusetts, and the varied and countless marine invertebrates which adhere to them below the water line.

In other portions of the hall will be found exhibits to illustrate certain facts made clear by Darwin and those who follow him: on the left, facing the entrance, Variation under Domestication, and on the right, Variation in Nature. The Struggle for Existence is portrayed by the meadow mouse surrounded by its many enemies, while the simpler features of the Mendelian Laws of Heredity are illustrated by the exhibits showing the inheritance of color in the common and sweet pea, and in a series of panels in a neighboring case showing the inheritance of coat-color in rats. Now return to the East Corridor, turn to the right, and underneath the stairway on the left enter.

A small room where the visitor will find the large Mainka Seismograph for recording earthquakes. This instrument was the gift of Emerson McMillin to the New York Academy of Sciences, and was deposited in the American Museum of Natural History by the Academy. Just beyond and north of Memorial Hall is the